History and Philosophy of Science
Eötvös University, Budapest
Philosophy of Science Colloquium
Room 6.54 (6th floor) Monday 4:00 PM

Pázmány P. sétány 1/A  Budapest Phone/Fax: (36-1) 372 2924 Location?


19 April  4:00 PM   6th floor 6.54   
Zoltán Gendler Szabó
  The Sage School of Philosophy, Cornell University
Pronouns and variables
(Névmások és változók)
When I teach introductory logic I tell my students that variables are sort of like pronouns in natural languages and when I teach introductory semantics I tell them that pronouns are sort of like variables
in the quantificational calculus. (Fortunately not many people take both classes, so I have never been caught.) But pronouns and variables are certainly not that similar: for one thing we usually have about a dozen pronouns in a natural language but infinitely many variables in the quantificational calculus. To match the expressive power of the quantificational calculus, natural languages must have some devices of treating different occurrences of the same pronouns as referring to  different things. The topic of my talk is how exactly natural languages pull off the trick.
Comments & Discussion.
  1. István A. Aranyosi
  2. Zoltán Gendler Szabó

26 April  4:00 PM   6th floor 6.54   
  Gábor Etesi
Department of Geometry, Institute for Mathematics
Budapest University of Technology and Economics
Geometric computability theory and its relationship with the strong cosmic censor conjecture
(Geometriai kiszámíthatóság-elmélet és kapcsolata az erős kozmikus cenzor hipotézissel)
In this lecture we overview the recent progress in geometric computability theory by enumerating those solutions to Einstein's equation which possess gravitational computers capable to perform computations beyond the Turing barrier. The class of such space-times is referred to as Malament--Hogarth space-times. Surprisingly, most of them are relevant also from a physical viewpoint.
Then we point out a natural link between the strong cosmic censor conjecture and Malament--Hogarth space-times. Namely, (i) the conformal class of an extendible maximal globally hyperbolic space-time contains a Malament--Hogarth space--time and (ii) for a Malament--Hogarth space-time the Geroch--Horowitz--Penrose formulation of the strong cosmic censor conjecture is valid. These together imply a quite weak version of the strong cosmic censor conjecture.
Finally we argue that albeit their physical and mathematical relevance, Malament--Hogarth space-times cannot be "stable" (in an appropriate sense) if the strong cosmic censor conjecture in its strongest form is valid.

The 60-minute lecture is followed by a 10-minute break. Then we hold a 30-60-minute discussion. The language of the presentation is indicated in the following way:
   English, except if all participants speak Hungarian
The participants may comment on the talks and are encouraged to initiate discussion through the Internet. The comments  should be written in the language of the presentation.

The organizer of the colloquium for the academic year 2003/2004: Miklós Rédei  (email: redei@hps.elte.hu)